BMW DCG - Double Clutch Gearbox
Wave goodbye to BMW''s SMG sequential manual gearbox and say hello to its new DCG double clutch gearbox. Known formally as the M Double-Clutch Transmission with Drivelogic, the seven-speed gearbox will make its debut in the 2009 M3 when the first cars begin arriving in mid-spring in coupe, convertible, and sedan form.
Key to the DCG''s operation are its two oil-cooled wet clutches, one for the even gears and one for the odd gears and reverse. During operation, the unused clutch remains open while the computer readies the next gear based on engine and road speed, allowing for a near instantaneous up- or downshifts, according to the automaker.
The computer is also programmed to adjust torque output and rev match between the engine and transmission in order to minimize power loss and increase shift smoothness. BMW says DCG is the first transmission of its kind designed to handle engine speeds of up to 9,000 RPM -- handy, given the M3''s 414 horsepower (in U.S.-spec) V-8 redlines at 8,400.
In addition to the lightning quick shifts, the DCG will offer plenty of features (or complexity, depending on the outlook). A choice of eleven shift modes, five automatic and six manual, will be included in the logic, including a launch control mode. Hopefully, the settings will be easier to find in the depths of iDrive than the SMG modes for the M5 and M6 have been.
Shifts can be initiated using either a standard lever or steering-wheel mounted paddles. In manual mode, shifting is aided by eight LED shift lights in the dash, six yellow and two red -- presumably, one for each 1,000 RPMs. These lights turn on one by one as engine speed increases and begin to flash when the engine approaches redline.
Owners brave enough to wade through the menus will be able to customize operation of the gearbox via the MDrive button, though it''s not clear what exactly can be changed. That said, if the DCG works as good as Volkswagen''s much-lauded DSG, the six-speed manual may eventually become little more than the choice of purists.
Sources:
http://www.motortrend.com/features/auto_news/2008/112_news180108_bmw_double_clutch_gearbox/index.html
http://www.caranddriver.com/var/ezwebin_site/storage/images/